Monday, November 18

The study of anatomy and physiology of skin is very essential for its healthy upkeep. Knowledge of the skin physiology helps us in understanding its complex functional mechanisms.

Skin anatomy and its histology gives insights into its basic structure and structural components.

Understanding biological processes of keratinocyte cell formation, growth, differentiation, migration and death is necessary for proper skin care. These studies also help in evolving methods to protect the skin and the inner organs from pathogens, toxic agents, oxidants, dehydrating circumstances, chemicals, environment, ultraviolet radiation and physical stress.

Study of skin structure

The human skin is composed of two layers, epidermis and dermis, which are unique in structure and function. The study of skin structure is important for clinical and cosmetic research. The study of the skin anatomy gives us insights into the complex mechanisms involved in its functional physiology.

Human complexion colors

Human complexion color is brought about by the concentration of melanin deposits and their various types. The deposition of pigments is mostly determined by four to six genes. These genes have several alleles, creating the possibility of several combinations, produce a great variety in the skin tone.

Physiology

The skin is the largest organ of the human body. It has a highly dynamic interface and covers and protects the internal organs by multiple mechanisms. Functioning as a physical barrier, it protects the body from the environmental elements and harmful microbes. Its functions include temperature regulation, sensory transduction and tactile discrimination.

Hydration and desquamation

Hydration and desquamation are necessary processes by which the skin is kept healthy, soft, smooth and supple. Any impediment to continuous hydration of the stratum corneum and continuous desquamation of dead cells will lead to many dermatological conditions like dry, thickened and scaly epidermis and dermatitis.

Histology and anatomy

Histology of skin deals with the microscopic study of the anatomy of its layers and cells. Skin consists of squamous keratinized outer layer called epidermis and fibrous and elastic inner connective tissue called dermis. The epidermis consists of five sublayers and dermis consists of two sublayers.

Epidermis

The epidermis is the outermost protective layer of the integumentary system. Epidermis has no blood vessels and is nourished by the diffusion of nutrients from the dermis. The anatomy of epidermis shows that keratinocytes form 90% of the cells. Melanocytes, melanosomes, melanin pigments, Langerhans cells and Merkel cells are also present in epidermis.

Five layers of epidermis

The epidermis is composed of five well defined sublayers. The outermost sublayer of the skin is stratum corneum. The sublayers in their descending order are stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum germinativum (stratum basale). Keratinocytes present in stratum basale undergo continuous mitotic cell division.

Epidermal keratinocyte cells

The cells constituting epidermis are mostly keratinocytes (95% of the cells). Keratinocytes function as stem cells (transit amplifying (TA) cells) and undergo continuous mitosis in stratum basale. These cells move upwards and differentiate into various layers and finally get sloughed off as dead skin.

Stratum corneum functions

Stratum corneum is the outermost layer of the epidermis. Being formed of functions as a barrier by the death of keratinocyte cells, stratum corneum functions as barrier to environment. It is multilayered and is composed of 15-20 layers flattened corneocytes. These corneocytes embedded within the multiple lamellar sheets of lipid matrix and are dead and anucleate.

Stratum lucidum functions

Stratum lucidum is a well defined epidermal layer found under the corneum in regions of thicker skin like the palms and soles. This transparent or translucent layer is composed of three to five tiers of dead flattened keratinocytes without distinct boundaries. They contain a clear intracellular protein called eleidin.

Stratum granulosum functions

Stratum granulosum is also known as granular layer due to visible granules present in its structure. It is found under the lucidum layer in the palms and soles and under corneum in the other areas of the skin. The keratinocytes present in stratum granulosum are the last layer of living cells which are in the process of losing their nuclei and dying.

Stratum spinosum functions

Stratum spinosum also known as prickle cell layer is the fourth tier from the exterior and is situated between stratum granulosum and germinativum (basale). Stratum spinosum is 5-10 keratinocyte cells in thickness. They are modified basal keratinocytes having large nuclei with very prominent nucleoli.

Stratum basale

Stratum basale (stratum germinativum) is the basal layer of epidermis. It contains one row of constantly dividing columnar or cubical undifferentiated keratinocytes with melanocytes and Langerhans or immune cells dispersed in between. The basement membrane separates the stratum basale from the inner dermis layer.

For more information on physiology of stratum basale read' Stratum basale'.

Reticular layer of dermis

The reticular layer of dermis is present below the papillary layer. It is the deepest part of the skin lying above the hypodermis. The reticular layer is thicker than the papillary layer and ranges from 1-3 mm in thickness. Dense irregular connective tissue and adipose tissue are the major constituents of the reticular layer.

Hypodermis layer

Hypodermis is the subcutaneous tissue forming the lowermost layer of our integumentary system. Though hypodermis is not considered as part of the skin, it is very essential for anchoring the skin to the body. Blood vessels and lymphatic vessels traverse hypodermis. Fibroblasts, fat cells (adipocytes) and leukocytes are present in hypodermis.

For more information anatomy and physiology of hypodermis read 'Hypodermis layer'.

Know your skin

Skin is a dynamic organ in a state of constant change. It is the largest organ in human body. In an average adult, its surface area including hair, nails and glands, may measures about 1.5-2 square meters (about 17-22 square feet) and weigh about 3.5 kilograms (about 8 pounds). It is a very complex structure made up of millions of different types of cells carrying out many varied functions.

For more information on its anatomy and physiology read 'Know your skin'.

Nourishing skin

For a lasting smooth clear complexion and a healthy glow of your face incorporate different fruits and vegetables into your diet on a daily basis. The Center for Nutrition Policy and Promotion recommends including half of our food plate with fruits and vegetables to get nutrients vital for the healthy maintenance of our body.

Wednesday, November 13

Acne is a very common skin problem faced by most of us, especially during teenage.
Areas of skin affected by acne are characterized by the presence of seborrhea, blackheads, whiteheads and pimples. Acne affected areas of skin have a great possibility of development of scars and blemishes.

Tackling acne is the most researched subject and so far there is no permanent solution for it. In this skin condition the tiny pores connecting the sebaceous follicles (hair follicles) to the skin surface get clogged. An increase in testosterone and the resultant androgen stimulation causes certain changes in skin structures consisting of a hair follicle. It leads to hyperkeratinization and formation of plugs of keratin and sebum leading to blockage of follicles and blemishes.

The clogged pores can cause enlargement of sebaceous glands and pave the way for inflammation and infection. Propionibacterium acnes, a naturally occurring commensal bacterium on the skin, can grow rapidly in such conditions and cause pimples and cysts.
It usually affects the areas of hyper sebaceous glands activity like face, neck, chest and back.

The inflammation and infection of the acne is followed by follicular rupture and perifollicular abscess formation. Then the healing process sets in with granulation tissue formation and matrix remodeling. In the new matrix, collagen protein has different fiber composition and alignment from that of damaged original protein of the tissue. Hence it stands out differently from the rest of the skin as scars, blemishes and hyperpigmentation.

Hormonal imbalance, harsh chemicals and environmental elements and general stress are some of the acne triggering factors. Homemade skin treatments can alleviate the acne and lighten scars and blemishes.

Types of acne scars

Acne scars and blemishes are brought about by the tissue repair mechanism. Depending upon the level of tissue damage and inflammation two different types of blemishes occur. Hypertrophic blemishes occur due to net increase in tissue formation resulting in raised thickened tissue on the skin. Atrophic types of blemishes with depressed areas of skin occur when there is net loss of tissue.

Natural remedies for acne scars

Proper exfoliation and inducing formation of new stratum corneum with natural products are the primary correctional methods. Fruit enzymes, alpha-hydroxy acids (AHAs) and beta-hydroxy acids present in natural products are used for the exfoliation. On reaching dermis, alpha-hydroxy acids and beta-hydroxy acids have been found to induce increased production of mucopolysaccharides and collagen and thereby increase the thickness of skin and remove blemishes.

Honey for acne scars

Honey is an excellent moisturizer. The high sugar supersaturation of honey makes it a difficult medium for bacteria to thrive in. Honey has exceptionally high antibacterial activity. Honey can be used as such for lightening blemishes or it can be blended with other kitchen ingredients like lemon juice, cinnamon powder, oatmeal or sandalwood powder. The ingredients help in exfoliation and honey induces new cell growth.

Manuka honey for acne

Skin moisture and exudation, help and set in motion glucose oxidase enzyme reaction and the resultant hydrogen peroxide (H2O2) production. Slow release of H2O2 provide antimicrobial activity without damage to living tissue. Apart from the antimicrobial hydrogen peroxide activity, manuka honey has high levels of antibacterial methylglyoxal (MGO or C3H4O2) and a synergistic component.

Tuesday, November 12

Nowadays makeup application is being done in a more scientific manner and the trend is to give natural look to the skin with added protection.

The very basic requirement for looking good is to have a healthy body and of course healthy skin. When the skin is healthy the requirement to use makeup will be less.

Eating balanced food, avoiding fats and fast foods, drinking sufficient water and exercising regularly can go a long way in improving the general health. Following a regular skin care regimen will help in maintaining a healthy skin. Regular cleansing, exfoliating and moisturizing is very important for keeping good natural looks.

The very purpose of the application is to bring out the best of your natural beauty. Makeup is, definitely, not to look like somebody else. Proper makeup application is an art by itself. Many women hesitate to apply them fearing that they may go wrong. However it is very easy to learn, if we understand the science behind it.

The best face makeup

The very first step in face application is to know the type of skin you have. There five types of skin namely, normal, oily, dry, mixed and sensitive tender skin. Each skin type requires a different approach in makeup. Oily skin require removal of excess oil before application.

Dry skin requires regular moisturization and periodic exfoliation to keep the skin soft and supple and scale free. In case of mixed skin the oily areas have to be blotted to remove face oil and the dry areas have to be generously moisturized. For tender skin, the cause of skin sensitivity has to be known before using any cream as there could be flareup of the condition.

How to do natural look makeup

Keep your skin healthy and consult a dermatologist to get rid of acne and other skin blemishes. Regularly cleanse, exfoliate and moisturize your skin. The cardinal natural makeup application tips is 'lesser the better'. Natural look is not 'no makeup' look. You have to aim for the appreciation of your beauty and not of your makeup.

To bring out your beauty you may be required to only remove some extra face oil or conceal some of the blemishes and fine lines. If you have dark circles and blemishes use a concealer sparingly. Smear the right foundation sparingly but blend well to avoid streaks. The foundation must merge with your skin tone.

Makeup application tips

Many professional training institutions have sprung up giving exclusive training to beginners as well as professional artists. With right type of inclination and intelligence, the art of makeup can be learnt at home. With progression
you will gain confidence evolve you own methods.

For getting that stunning look prepare your face well before application. Moisturize your face and wait for 10-15 minutes before makeup. You can use primer to even out the skin, specially in wrinkle areas. Use suitable brush or use finger tips to smear primer evenly on the face.

Friday, November 8

Hypopigmentation (hypomelanosis) is the loss of or reduction in production of skin pigment. Depending upon the type of skin disorder, hypopigmentation may be total, partial or localized.

Hypomelanosis may be due to a specific cause as in albinism (genetic) or due to an unknown cause as in idiopathic guttate hypomelanosis. The affected skin area may be well defined and geographic in shape with total loss of pigment as in the case of vitiligo. In some cases hypopigmentation may be congenital. The congenital lack of pigment is stable and nonprogressive and it can be either total or localized.

Infections of the skin, especially fungal infections like tinea versicolor, can cause hypomelanosis. Post inflammatory hypopigmentation (PIH) is caused as a result of inflammation, damage or trauma to the skin as in the case of infections, dermatitis, burns, blisters and pimples. In some cases, improperly conducted chemical or cosmetic laser treatments can cause skin damage and hyperpigmentation or hypomelanosis. Here in this post various skin conditions leading to hypopigmentation are briefly described.

White discoloration on skin

White discoloration of skin occurs due to loss of or reduction in melanin pigment and hypomelanosis on the skin. The melanin pigment in the skin gives the skin coloration ranging from white to dark black. The amount of melanin to be produced by the skin and the color of a person are decided by the genetic factors.

Albinism

Albinism disorder is an inherited hypomelanosis condition wherein little or no pigment is produced by the body. Albinism involves different genes and hence there are different types.
Albinos have various degrees of vision impairment and tender skin. Some affected persons may be nearly blind. The retina of albinos may be impaired during the development.

Albinism disorder types

Albinism, hypomelanosis disorders, are of several types and basically all types are caused by genetic defects. There are 15 genetic locations in the chromosomes, the defects of which are associated with albinism. Oculocutaneous type of albinism involves hypomelanosis of eyes (ocular), skin (cutaneous) and hair. The mutation of GPR143 gene on X chromosome causes ocular albinism (OA1).

Idiopathic guttate hypomelanosis

Idiopathic guttate hypomelanosis are very common hypopigmentation spots seen usually on the exposed parts of the body like shin and forearm. These hypomelanosis spots are drop-like in appearance and are small in size (2-5 mm). These hypopigmentation white spots begin to appear around the age of 30 years and are found to affect far more women than men.

Idiopathic guttate hypomelanosis - causes

The causes for this hypopigmentation disorder are not exactly known. As these hypomelanosis white spots are generally found on the exposed parts of the body, one possible cause may be excessive exposure to sunlight. These spots start appearing in the late twenties and early thirties. Hence, aging process could be one of the possible causes of hypomelanosis.

Idiopathic guttate hypomelanosis - treatment

These hypopigmentation white spots are harmless and do not require any treatment. However for individuals conscious about aesthetic appearance treatments for hypomelanosis are available.
Treatments includes application of topical steroids or retinoids, dermabrasion or microdermabrasion, cryotherapy, cosmetic cover-up, surgery and grafting.

Nevus depigmentosus

Nevus depigmentosus is white spot with hypopigmentation. Nevus depigmentosus is congenital, benign and non progressive. These patches usually appear on the trunk, hands and feet. In most of the cases they are present at the time of birth. Functional and morphological anomalies of melanocytes and melanosomes appear to cause this condition.

Pityriasis alba

Pityriasis alba is an atopic dermatitis with hypopigmentation. Pityriasis alba affects children mostly on their face. Children of the age between 3 and 16 years are generally affected. Initially the hypopigmentation spots may appear red or pink. Later these white patches fade and appear pale and dry.

Pityriasis alba - causes

The real cause of pityriasis alba is not known. A number of possible causes are being postulated. The microscopic analysis of the skin scrapings rules out the involvement of bacteria or fungi. Further studies have revealed that there is reduction in the number of functional melanocytes and decrease of melanosomes in size and number.

Pityriasis alba - symptoms

Pityriasis alba initially appear as raised red patches which after some days become flat and pale. The hypopigmentation is partial in the spots. The hypomelanosis macules are usually limited to face, especially on the cheeks, around mouth and chin. On closer examination these white patches show small dry scales.

Pityriasis alba - treatment

In most of the cases pityriasis alba resolves by itself without any treatment after some time. However the pigmentation of the hypopigmentation spots of the affected skin will be slow and take considerable time. The application of moisturizers can help in dehydrating the skin and reduce and prevent dryness as well as scale formation.

Tinea versicolor

Tinea versicolor (pityriasis versicolor) are fungal infections. Tinea versicolor is superficial, benign, common, recurrent and noncontagious. This infection is usually restricted to stratum corneum layer of the epidermis. Tinea versicolor characterized by patches of hypomelanosis. Sometimes these spots may be hyperpigmented.

Tinea versicolor - causes

Tinea versicolor (pityriasis versicolor) is caused by yeast variety of fungi belonging to Malassezia group. Malaassexia furfur and M.globosa are the main causative fungi. They are part of the normal resident flora of the human skin. Under certain conditions like heat and humidity, these fungi can proliferate rapidly and cause the infection and hypopigmentation.

Tinea versicolor - symptoms

Tinea versicolor appears as itchy patches of hypopigmentation or hyperpigmentation.
The flat macules are of circular and oval shape with sharp margins. The infection worsens in hot and humid conditions with intense itch. It is superficial infection affecting the stratum corneum layer of the epidermis. Usually fine scales are present.

Tinea versicolor - treatment

Tinea versicolor can be effectively treated with a wide variety of medications. In early stages topical creams and lotions available over the counter can be bought and applied. Some of the topical applications are, tea tree oil, selenium sulphide shampoo,
clotrimazole cream, terbinafine cream, cassia alata leaves and ciclopirox olamine.

Vitiligo (leucoderma)

Vitiligo (leucoderma) is a skin disorder in which hypopigmentation patches occur due to
loss of melanin pigment of the skin. The loss of skin pigmentation, can be focal, segmental and non-segmental. These white patches of hypopigmentation may spread and grow over time to cover greater area of the body.

Vitiligo - causes

The basic cause of vitiligo is the stoppage of melanin pigment production or death of melanocytes. Due to some physiological conditions, hypomelanosis patches form and grow. Possible factors causing this hypopigmentation disorder are, autoimmune diseases, thyroid disorders, hereditary and genetic disorders, stress and environmental conditions.

Vitiligo - signs

Signs of vitiligo include the development of flat hypopigmentation patches without any scale formation. These hypomelanosis patches occur prominently on the extremities. Though vitiligo appears initially as small spots, it progresses and spreads all over the body. The orifices of the body as well as the sun the exposed areas are mostly affected by hypopigmentation.

Vitiligo - diagnosis

Hypopigmentation of face particularly around mouth, eyes, nostrils and ears indicate the possibility of development of vitiligo. The hypomelanosis of the orifices of the body like mouth, nostrils, ears, umbilicus, anal opening and genital opening could be the indicator of development of leucoderma disease.

Vitiligo - camouflage by micropigmentation

For focal, non progressive and static vitiligo micropigmentation (camouflage tattoo) can be successfully done. Colors like black, white (titanium oxide), camel yellow, brown (iron oxide), red (mercuric sulphate, cinnabar) are used in vitiligo camouflage. The expertise of the tattoo professional play a great part in the success of this tattoo procedure for treating hypopigmentation.

Vitiligo - cure - repigmentation

In patients with focal or segmental vitiligo, autologous melanocyte transplantation and
repigmentation of the hypopigmentation spots can be tried. Patient's own melanocytes are harvested from his normal areas of skin and cultured in a medium. These cultured melanocytes are introduced into hypomelanosis spots for further growth and repigmentation.

Vitiligo research

Vitiligo research is now focused on autologous melanocyte transplantation, stem cell transplantation and genetic aspects of vitiligo. undifferentiated melanocytes or stem cells are present in the outer root sheath of hair follicle. The transplantation of these stem cells will repopulate the deficient skin with active melanocytes at the hypopigmentation sites.

Many skin diseases, disorders and problems resolve by themselves, requiring no treatment. However some situations require medical intervention in order to stop aggravation of the skin disease. The basic knowledge of the various skin disorders and their differentiation guides us in the follow up action to be taken.

Acne scars

Acne scars are either hypertrophic or atrophic. The tissue repair mechanism of the skin based on the level of inflammation and damage causes either of the two types of acne scars. Hypertrophic types of scars are characterized by raised thickened tissue formation on the skin. Atrophic types of scars are depressed areas of skin.

In hypertropic types of acne scars there is over production of collagen and increased tissue formation resulting in raised level of skin. Atrophic types of scars are characterized by loss of skin tissue.

Albinism

Albinism is an inherited disorder wherein little or no pigment is produced by the body, affecting the color of the skin, eyes and hair. Albinism is usually associated with debilitating health and vision issues. This genetic disorder is found to affect individuals of all racial and ethnic backgrounds.

Albinism involves different genes and hence there are different types. In oculocutaneous albinism (OCA) pigmentation of the skin, hair and eyes is affected. Ocular albinism (OA) is a rare disorder wherein only the pigment in the eyes is affected.

Angioedema

Allergic reaction to food or medicines can cause edema and swelling of the subcutaneous tissue, known as angioedema. Unlike the allergic reactions in hives which are superficial, angioedema reactions are below the skin. The angioedema swellings may range from small spots to large lesions of several inches in diameter.

Angioedema swellings usually occur on the face, around the eyes and lips, inside the mouth and throat and on the tongue. Swellings affecting the mouth and throat may block the airway and become life threatening.

Argyria

The presence of silver in the body causes a rare blue skin disorder known as argyria.
Protracted excessive exposure to metallic silver, silver salts and silver compounds or their ingestion causes argyria. Apart from skin, sclera, conjunctiva, mucous membranes, nail beds, gums and visceral organs also may get affected with argyria.

Generalized form of argyria results from ingestion of silver salts and silver compounds for prolonged periods. Localized argyria is caused when there is continuous localized excessive skin contacts with silver and its compounds.

Chronic hives

Hives (aka urticaria) are itchy pink-red welts (wheals) appearing on the skin. If the problem of swelling and redness persists or recurs for more than six weeks, it is considered chronic. Allergic reactions triggered by food, chemicals, physical stimuli or medicines cause hives.

However on many incidences the cause and the trigger are not known or idiopathic. The lesions are pink-red in color and appear as well-marked round, oval or generalized raised skin swellings. In some patients it may last or recur for years.

Cellulitis

Cellulitis is the 'inflammation of the cells' of dermal and subcutaneous tissues. The
inflammation is usually caused by Streptococcus pyogenes and Staphylococcus aureus.
The area of skin affected by cellulitis is characterized by swelling, redness and pain. If the infection is severe, the inflammation is accompanied by febrile illness.

Cellulitis caused by the streptococcus and staphylococcus bacteria spreads fast due to the availability of the cell nutrients. The release of the metabolic wastes, toxins and enzymes by the microbes damage the surrounding skin tissues.

Fordyce spots

Some sebaceous glands on the skin are formed without connection to hair follicles. They are known as Fordyce spots (Fordyce granules or Fordyce disease). Fordyce spots are named after John Addison Fordyce, an American dermatologist. Fordyce granules are ectopic glands and open directly onto the skin surface.

Fordyce spots are seen in both men and women, but are very common in men and about 80% of them have it.
Fordyce spots are benign, painless and usually appear as small raised pale, white bumps on the skin on lips, nipple or genitalia.

Hemangioma

Hemangioma meaning 'blood-vessel-tumor' is a benign tumor, usually appears on the skin, especially on the head, face and neck. It is formed by the abnormal growth and buildup of blood vessels. It may form on the top layer of skin or form deep inside the skin. Hemangioma may also form on the internal organs like liver, spine and vertebrae.

Hemangioma skin lesions may be present at birth or develop in the early infancy. These lesions grow rapidly for twelve months followed by a resting phase of about twelve months. Then the involution phase starts and the lesions disappear by ten years.

Hereditary angioedema

Hereditary angioedema (HAE) is a rare genetic disorder causing episodic attacks of cutaneous and submucosal swellings. Hereditary angioedema is found to affect up to 0.01% of the population with mortality ranging at 15-33%. The swellings affect the face, extremities, respiratory tract, genitalia and gastrointestinal tract.

Up to 75% of HAE clinical manifestations are familial inheritances. Fresh mutations contribute to 25% of the cases. In some instances involving the throat and mouth, HAE can block airways and become life threatening.

Idiopathic guttate hypomelanosis

Idiopathic guttate hypomelanosis are hypopigmented pale white spots usually appearing on skin of shins and forearms. The reasons for the development of these spots is not clearly known (idiopathic). Idiopathic guttate hypomelanosis spots are 'drops' like in appearance and are small in size (2-5 mm).

In some rare cases macules as big as 10 mm in diameter have been observed. It is believed that excessive exposure to sunlight might be a causative factor or a trigger. This disorder usually observed from late twenties of age.

Methemoglobinemia

Methemoglobinemia (aka hemoglobin M disease or Erythrocyte reductase deficiency) is a form of blood hemoglobin disorder. The oxygen carrying capacity of Red blood cells (RBC) is reduced in this disorder and the oxygen supply to the tissues including skin is affected. This leads to bluish discoloration of skin and cyanosis.

Acquired form of methemoglobinemia may be caused on exposure to certain medicines, food products and chemicals. Hereditary form of methemoglobinemia is caused either due to erythrocyte reductase deficiency or generalized reductase deficiency.

Affecting both boys and girls equally, baby milk spots usually disappear within 15-30 days and may not need any treatment. Milia usually appear on the skin around the eyes, forehead, cheeks, chin and nose. About half of the newborn develop milia.

Mongolian spot

Mongolian spot (aka congenital dermal melanocytosis or Mongolian birthmark) is a benign asymptomatic skin birthmark. Mongolian blue spot may be present at birth or appears shortly thereafter. These skin macules of hyperpigmentation, usually appearing on lumbosacral area and buttocks, are flat and irregular in shape with indistinct wavy border.

Mongolian spot may also occur on shoulders and other parts of the body. Usually head, face, palms and soles are spared. Erwin Bälz, who was a German and was a personal physician to the Japanese Imperial Family, discovered and named 'Mongolian spot'.

Nevus depigmentosus

Nevus depigmentosus is a white macule, patch or spot lacking pigmentation. Nevus depigmentosus is congenital, benign and non progressive skin lesion. The cause of this hypopigmentation skin disorder is not fully understood. However during the lifetime of the affected individual, nevus depigmentosus is stable in size as well as in distribution.

Nevus depigmentosus patches usually grow only in proportion to the growth of the body.Though the macules can form on any part of the body, they are found to usually affect the skin of trunk, hands and feet.

Nevus simplex

Nevus simplex (aka nevus flammeus nuchae or salmon patches) are very common birthmarks found in about 30% newborns. When found on the nape of the neck they are known as 'stork bite'. These vascular birthmarks are congenital skin capillary malformations. They are caused by the dilation and stretching of capillaries under the skin.

Though nevus simplex may appear anywhere on the body, in most of the incidences they are found on the nape of the neck, forehead, on or around eyelids, on or around nose and upper lip. Salmon patches are pink colored, flat and irregularly shaped skin lesions.

Pityriasis alba

Pityriasis alba is a common atopic dermatitis mostly affecting children of the age between 3 and 16 years. Pityriasis alba appears as fine-scaled oval and round dry pale white patches or spots on the facial skin of the children. More number of boys are affected than girls and is more prevalent in lighter-skinned individuals.

Pityriasis alba may be colored pink or red initially. Later the redness fades leaving a pale hypopigmented patch usually on the cheek, chin and mouth areas. The border of the patches is not clearly marked and blends gradually with the normal skin.

Raynaud's disease

Raynaud's phenomenon or Raynaud's disease involves the arteries of fingers and toes.
In this disease of circulatory system the blood vessels of the fingers and toes undergo sudden vasospasm restricting the blood supply. Raynaud's disease was discovered by a French doctor A. G. Maurice Raynaud (1834–1881).

Hyperactivity of sympathetic nervous system leads to constriction of peripheral arteries and the bluish discoloration on skin of toes and fingers. The condition may last from a few minutes to several hours. In some rare cases ear lobes, nose, lips and nipples may also be involved.

Rhinophyma

Rhinophyma is the large, erythemic, bulbous, uneven swelling of the nose. Phymatous rosacea in its advanced-stage can cause rhinophyma. The Greek word 'rhis' means nose and 'phyma' meaning growth, swelling or bulb on the skin. People of English, Irish and Scottish descent are more prone to develop rhinophyma.

Rhinophyma is found to affect middle-aged and elderly men. It rarely occurs in women. Rhinophyma is the hypertrophy of the sebaceous glands on the tip of the nose. Rhinophyma can become unsightly and may even obstruct respiration and vision.

Tactile defensiveness

Tactile defensiveness is due to the exaggerated tactile sensitivity experienced by the affected patient. It is a sensory processing disorder found in about 75% of the boys with 'fragile X syndrome' and some girls with full X mutation. The affected patient develops a defensive attitude to touch perception and dislikes being touched.

This skin sensory disorder of the midbrain region affects the filtering of the incoming stimuli. This causes overemphasized perception of the touch stimuli of the skin, resulting in great distress, misery and discomfort.

Tinea versicolor (pityriasis versicolor)

Tinea versicolor (aka pityriasis versicolor) are usually superficial, benign, common, recurrent and not contagious macules or patches formed on the skin. They are fungal infections affecting the stratum corneum layer of the epidermis. Tinea versicolor disease is characterized by hyperpigmented or hypopigmented macules and colored patches.

Tinea versicolor infection is caused mainly by the Malassezia globosa fungus and in a small number of cases Malassezia furfur has been found to be the causative fungus. These skin patches are versicolored appearing in multi colors of white, creamy, pale pink and brown.

Vitiligo

Vitiligo (aka leucoderma or leukoderma) is a skin disorder wherein there is loss of skin pigment causing white depigmented patches. In vitiligo, due to some physiological conditions, genetic disorders, thyroid disorders, psychological stress or autoimmune diseases, there is stoppage of melanin pigment production or death and loss of the melanocytes.

About 1-2% of the world's population is affected by the loss of skin pigment. Patients suffering from autoimmune diseases and thyroid disorders are prone to develop vitiligo. It equally affects both the genders and appears prominent in dark-skinned patients.